N.H. 4 NO 3
Potassium, sodium, calcium and ammonium nitrates are called nitrates . For example, saltpeter: KNO 3 – potassium nitrate (Indian saltpeter), NaNO 3 – sodium nitrate (Chilean saltpeter), Ca(NO 3) 2 – calcium nitrate (Norwegian saltpeter), NH 4 NO 3 – ammonium nitrate (ammonium or ammonium nitrate, there are no deposits of it in nature). German industry is considered the first in the world to obtain salt NH4NO3 from nitrogen N 2 air and hydrogen water suitable for plant nutrition.
Physical properties
Nitrates are substances with predominantly ionic crystal lattices. Under normal conditions, these are solid crystalline substances, all nitrates are highly soluble in water, strong electrolytes.
Obtaining nitrates
Nitrates are formed by the interaction of:
1) Metal + Nitric acid
Cu + 4HNO 3 (k) = Cu(NO 3) 2 + 2NO 2 + 2H 2 O
2) Basic oxide + Nitric acid
CuO + 2HNO 3 = Cu(NO 3) 2 + H 2 O
3) Base + Nitric acid
HNO 3 + NaOH = NaNO 3 + H 2 O
4) Ammonia + Nitric acid
NH 3 + HNO 3 = NH 4 NO 3
5) Salt of a weak acid + Nitric acid
In accordance with a number of acids, each previous acid can displace the next one from the salt :
2 HNO 3 + Na 2 CO 3 = 2 NaNO 3 + H 2 O + CO 2
6) Nitric oxide (IV) + alkali
2NO 2 + NaOH = NaNO 2 + NaNO 3 + H 2 O
in the presence of oxygen -
4 NO 2 + O 2 + 4 NaOH = 4 NaNO 3 + 2 H 2 O
Chemical properties of nitrates
I . Common with other salts
1) C metals
The metal located in the activity series to the left displaces the following from their salts:
Cu(NO 3) 2 + Zn = Cu + Zn(NO 3) 2
2) WITH acids
AgNO 3 + HCl = AgCl↓ + HNO 3
3) With alkalis
Cu(NO 3) 2 + 2NaOH = Cu(OH) 2 ↓ + 2NaNO 3
4) C c olami
2AgNO 3 + BaCl 2 = Ba(NO 3) 2 + 2AgCl↓
II . Specific
All nitrates are thermally unstable. When heated They decompose with the formation of oxygen. The nature of other reaction products depends on the position of the metal forming the nitrate in the electrochemical voltage series:
1) Nitrates of alkali (exception - lithium nitrate) and alkaline earth metals decomposes to nitrites:
2NaNO3 = 2NaNO2 + O2
2KNO 3 = 2 KNO 2 + O 22) Nitrates of less active metals from Mg to Cu inclusive and lithium nitrate decompose to oxides:
2Mg(NO 3) 2 = 2MgO + 4NO 2 + O 2
2Cu(NO 3) 2 = 2CuO + 4NO 2 + O 2
3) Nitrates of the least active metals (to the right of copper) decompose to metals:
Hg(NO 3) 2 = Hg + 2NO 2 + O 2
2AgNO3 = 2Ag + 2NO2 + O2
4) Ammonium nitrate and nitrite:
Ammonium nitrate decomposes depending on temperature as follows:
NH 4 NO 3 = N 2 O+ 2H 2 O (190-245 ° C)
2NH 4 NO 3 = N 2 + 2NO + 4H 2 O (250-300 ° C)
2NH 4 NO 3 = 2N 2+ O 2 + 4H 2 O (above 300 ° C)
Ammonium nitrite:
NH 4 NO 2 = N 2+ 2H 2 O
Additionally:
Ammonium nitrite decomposition
Exceptions:
4LiNO 3 = 2Li 2 O + 4NO 2 + O 2
Mn(NO 3) 2 = MnO 2 + 2NO 2
4Fe(NO 3) 2 = 2Fe 2 O 3 + 8NO 2 + O 2
Qualitative reaction to nitrate ion NO 3 – – interaction of nitrates with copper metal when heated in the presence of concentrated sulfuric acid or with a solution of diphenylamine in H2SO4 (conc.).
Experience. Qualitative reaction to the NO 3 – ion.
Place a stripped copper plate, several crystals of potassium nitrate, and add a few drops of concentrated sulfuric acid into a large dry test tube. Close the test tube with a cotton swab moistened with a concentrated alkali solution and heat.
Signs of a reaction - brown vapors of nitrogen(IV) oxide appear in the test tube, which is best observed on a white screen, and greenish crystals of copper(II) nitrate appear at the copper-reaction mixture boundary. .
The following reaction equations occur:
KNO 3 (cr.) + H 2 SO 4 (conc.) = KHSO 4 + HNO 3
Most people are familiar with nitrates due to their content in food. But in fact, they are used in various fields of industry and agriculture. Read about their reactions, solutions, properties, benefits and harms in the article.
What are nitrates?
These are salts of nitric acid, which contain all living organisms, as well as soil and water. In plant nutritional media, nitrate content is mandatory. They are delivered to the human body by water and vegetables.
The production of nitrates is the result of the action of nitric acid on substances such as salt, metal, as well as hydroxides and oxides. Nitrates, for the most part, are highly soluble in water. In solution, nitrate oxidizing properties are practically absent, but in the solid state, nitrates are strong oxidizing agents. They are stable at normal temperatures. Melting of nitric acid salts occurs at a temperature of 200-600 ° C, often with simultaneous decomposition.
This is a substance of inorganic origin, a salt of divalent copper and nitric acid. This nitrate is an anhydrous, hygroscopic substance with colorless crystals, but when they absorb moisture, they acquire a blue color, forming crystalline hydrates. Found in nature as minerals: ruaite, gerhardtite.
This nitrate is a substance that forms solid crystals that dissolve well in water and other media, such as ethanol, ethyl acetate, methanol and others. Copper nitrate is used in the synthesis of organic and inorganic compounds. The substance is used by the textile industry for dyeing and mordanting fabrics. In agriculture, it is used for the production of fungicides, which are used to combat diseases of fungal origin in plants.
Chemical properties of copper nitrate
This substance has the following properties:
- Decomposition that occurs when nitrate is heated. As a result of the reaction, copper oxide and nitrogen dioxide are formed, which are used to produce nitric acid in the laboratory.
- Hydrolysis, in which copper nitrate dissociates into ions in water.
- Exchange reactions that result in ion exchange. For example, if a substance reacts with an alkali, a blue precipitate forms, with sodium phosphate - blue, with a concentrated ammonia solution - dark blue, with yellow blood salt - red.
Copper nitrate: methods of production
Under industrial conditions, the compound is obtained as a result of the decomposition of naturally occurring minerals such as ruaite and gerhardtite. This technique is not used in laboratories because technical conditions do not allow it. It will be easier to dissolve metallic divalent copper, its oxide and hydroxide. To obtain a solution, high concentration nitrate acid is used.
Copper nitrate can be obtained by a reaction using copper metal and dinitrogen tetroxide. An important condition for this is the temperature: it should be 80 O C.
Barium
Barium nitrate is a salt of nitric acid, called barium nitrate or barium nitrate. The substance is a colorless, non-hygroscopic crystal with a cubic lattice. It is soluble in water, but at higher temperatures this process occurs faster. It does not dissolve in high concentration nitric acid and alcohol. The mass of nitrate (molar) is 261.337 g/mol, and the density is 3.24 g/cm3. The melting point is 595 O C. It is obtained by industrial and laboratory methods. In nature, it occurs as the mineral nitrobarite, which is rare. It was first discovered in Chile.
Barium nitrate: chemical reactions
This substance reacts with many compounds:
- With sulfuric acid, resulting in the precipitation of barium sulfate and the formation of a solution of nitric acid.
- If potassium sulfate is taken for the reaction, then as a result of the reaction its nitrate is formed, and barium sulfate precipitates.
- Reacts with nitric acid and barium sulfate.
- Hydrochloric acid and barium nitrate never react.
Barium nitrate: application
The production of barium peroxide and oxide is the main use of nitrates. The reactions by which this occurs are accompanied by the release of toxic substances. Therefore, the premises must have strong ventilation. Barium peroxide is used for the production and bleaching of fabrics, paper, and is used in the composition of glazes for ceramic products to firmly fix them. Barium nitrate is widely used in pyrotechnics to produce green fireworks. However, it is important to take into account that the hygroscopicity of the substance is low, so storage requires dry rooms with good ventilation. Barium nitrate, in addition, is a sought-after substance for the production of explosive materials.
When working with a reagent, you should always remember the danger that awaits a person if it is handled incorrectly. A separate place is chosen for barium nitrate in the storage room, since this nitrate ignites very easily. If a fire occurs, the fire should be extinguished with plenty of water.
Silver nitrate
This substance is a rhombic-shaped crystal without color. Their appearance resembles plates or odorless white crystalline rods. Silver nitrate has a good ability to dissolve in water and other liquids; for this, 20 O C above zero is sufficient. Its decomposition occurs at a temperature of 300 O C. When exposed to light, it darkens. The substance is obtained by reacting silver and nitric acid. Nitrate is thus the result of dissolving silver in acid.
Pharmacological properties of silver nitrate
This substance has the following properties, due to which it is widely used in medicine:
- Antiseptic.
- Bacterial.
- Anti-inflammatory.
- Cauterizing.
- Knitting.
- Antimicrobial.
Nitrate is used to make lapis. Upon contact with the skin, black spots appear on it, and with prolonged contact, deep burns appear. Lapis is used in medicine to cauterize small wounds, cracks, papillomas, growths, moles, acne, and warts. Nitrate is widely used in dentistry, homeopathy and other areas for the treatment of various diseases.
Past use of silver nitrate
Hellstone is another name for a substance that has been used in medicine for a long time. Silver nitrate solution was previously used by many branches of medicine. Due to its actions, it was used in the treatment of stomach ulcers. Patients were prescribed a solution in small doses for oral administration. They were instilled into the eyes of newborn children, and were also used to prevent gonorrheal conjunctivitis in infants.
Currently, this solution is used to a limited extent, since many other products are produced that replace it. But the cauterizing property of the drug is still given great importance: they cauterize erosions and non-healing wounds. Silver nitrate preparations are most often prescribed to patients with diseases of the nose and pharynx.
How is barium nitrate produced?
There are several ways:
- The first method is based on the reaction of sodium nitrate (saltpeter) with barium chloride. A hot solution is obtained, it is cooled, and then filtered and dried. After this, the filtered material is oxidized with nitric acid. Then filtration and drying are carried out again.
- The basis of the second method is the use of barium sulfate. To obtain barium nitrate, two reactions are carried out, not one.
- The third method is used in laboratories. To obtain anhydrous barium nitrate, water molecules are removed. First, the process of evaporating the solution and then drying is carried out.
Nitrates in the human body
Nitrates are substances whose excessive content in the body can cause serious poisoning. In addition, as a result of the action of microorganisms, nitrates can be converted into nitrites. The intestines are prone to such a transformation, especially with low acidity. Nitrites interact with hemoglobin, resulting in the formation of methemoglobin, which does not have the ability to transport oxygen. In this situation, oxygen starvation occurs in the body. The normal level of methemoglobin in the blood is 2%. If its content rises to 30, severe poisoning will occur, and to 50 - death.
Nitrates in food
It is mistakenly believed that only purchased vegetables, for the cultivation of which various fertilizers were used, are rich in nitrates. But it is not so. In domestic vegetables, for the growth and development of which organic fertilizers were used, nitrates are also present. They pass into the soil from manure or chicken droppings, and from there to vegetables.
Different fruits and even individual parts of them contain nitrates of varying concentrations. For example, there are more of them in the peel of cucumbers, in the stalk and thick veins of cabbage, in the pulp of melon or watermelon, located closer to the rind. The appearance of a vegetable can be deceiving. Large, smooth fruits contain more nitrates, so it is better to choose medium-sized ones. If the surface of the vegetable is covered with compactions, and the cut has an uneven color, then the nitrate content in the vegetable is high. Soaking and heat treatment with the lid open helps reduce their number.
Application of nitrates
The main use of saltpeter was in agriculture. Here nitrates are used as fertilizers. The nitrogen that plants take from salt is necessary for them to build cells and create chlorophyll. In addition, glass and medicines are obtained from nitrates. They are used to produce explosives, pyrotechnics, and fuel components for rockets. They are used as food additives in the production of sausages and other products.
Each of us at least once in our lives has encountered the unpleasant consequences of eating foods with nitrates. For some, such a meeting continued with a mild intestinal disorder, while others managed to end up in the hospital and for a long time looked warily at any fruits and vegetables purchased at the market. The pseudo-scientific approach and lack of awareness make saltpeter a monster capable of even murder, but it’s worth getting to know these concepts better.
Nitrates and nitrites
Nitrites are salts of nitric acid that have the form of crystals. They dissolve well in water, especially hot water. On an industrial scale, they are obtained by absorbing nitrous gas. They are used to produce dyes, as an oxidizing agent in the textile and metalworking industries, and as a preservative.
The role of nitrates in plant life
One of the four main elements that make up a living organism is nitrogen. It is necessary for the synthesis of protein molecules. Nitrates are salt molecules that contain the amount of nitrogen the plant needs. When absorbed by the cell, the salts are reduced to nitrites. The latter, in turn, reach ammonia. And it, in turn, is necessary for the formation of chlorophyll.
Natural sources of nitrates
The main source of nitrates in nature is the soil itself. When the organic substances it contains are mineralized, nitrates are formed. The speed of this process depends on the nature of land use, weather and soil type. The soil does not contain much nitrogen, so environmentalists are not concerned about the formation of significant amounts of nitrates. Moreover, agricultural work (harrowing, disking, constant use of mineral fertilizers) reduces the amount of organic nitrogen.
Anthropogenic sources
Conventionally, anthropogenic sources can be divided into agricultural, industrial and municipal. The first category includes fertilizers and livestock waste, the second category includes industrial wastewater and production waste. Their impact on environmental pollution is not the same and depends on the specifics of each specific region.
Determination of nitrates in organic materials gave the following results:
More than 50 percent is the result of the harvesting campaign;
- about 20 percent - manure;
- municipal municipal waste is approaching 18 percent;
- everything else is industrial waste.
The most serious damage is caused by nitrogen fertilizers, which are applied to the soil to increase yield. The breakdown of nitrates in soil and plants produces enough nitrites to cause food poisoning. Agricultural intensification is only making this problem worse. The highest levels of nitrates are noticed in main drains that collect water after irrigation.
Impact on the human body
Nitrates and nitrites first became compromised in the mid-seventies. Then in Central Asia, doctors recorded an outbreak. During the investigation, it was found that the fruits were processed and, apparently, a little overdone. After this incident, chemists and biologists began to study closely the interaction of nitrates with living organisms, in particular humans.
- In the blood, nitrates interact with hemoglobin and oxidize the iron it contains. This produces methemoglobin, which cannot carry oxygen. This leads to disruption of cellular respiration and oxidation
- By disrupting homeostasis, nitrates promote the growth of harmful microflora in the intestines.
- In plants, nitrates reduce the content of vitamins.
- An overdose of nitrates can lead to miscarriage or impaired sexual function.
- In chronic nitrate poisoning, a decrease in the amount of iodine and a compensatory enlargement of the thyroid gland are observed.
- Nitrates are a trigger factor for the development of tumors of the digestive system.
- A large dose of nitrates can immediately lead to collapse due to a sharp expansion of small vessels.
Metabolism of nitrates in the body
Nitrates are ammonia derivatives, which, when entering a living organism, are integrated into the metabolism and change it. In small quantities they are not of concern. With food and water, nitrates are absorbed in the intestines, pass through the bloodstream through the liver and are excreted from the body by the kidneys. In addition, in nursing mothers, nitrates pass into breast milk.
During metabolism, nitrates are converted into nitrites, oxidize iron molecules in hemoglobin and disrupt the respiratory chain. In order for twenty grams of methemoglobin to be formed, only one milligram is enough. Normally, the concentration of methemoglobin in the blood plasma should not exceed a couple of percent. If this indicator rises above thirty, poisoning is observed; if above fifty, it is almost always fatal.
To control the level of methemoglobin in the body, there is methemoglobin reductase. This is a liver enzyme that is produced in the body starting from three months of life.
Permissible norm of nitrates
Of course, the ideal option for a person is to avoid getting nitrates and nitrites into the body, but in real life this does not happen. Therefore, doctors at the sanitary-epidemiological station established standards for these substances that cannot harm the body.
For an adult weighing more than seventy kilograms, a dose of 5 milligrams per kilogram of weight is considered acceptable. An adult can ingest up to half a gram of nitrates without serious health consequences. In children, this figure is more average - 50 milligrams, regardless of weight and age. At the same time, a fifth of this dose will be enough for an infant to be poisoned.
Routes of entry
You can get poisoning with nitrates through the nutritional route, that is, through food, water and even medications (if they contain nitrate salts). More than half of the daily dose of nitrates enters a person with fresh vegetables and canned food. The remaining dose comes from baked goods, dairy products and water. In addition, a small part of nitrates are metabolic products and are formed endogenously.
Nitrates in water are a reason for a separate discussion. It is a universal solvent, therefore, it contains not only useful minerals and trace elements necessary for normal human life, but also toxins, poisons, bacteria, helminths, which are the causative agents of dangerous diseases. According to the World Health Organization, about two billion people get sick every year due to poor quality water, and more than three million of them die.
Chemical fertilizers containing seep through the soil and end up in underground lakes. This leads to the accumulation of nitrates, and sometimes their amount reaches two hundred milligrams per liter. Artesian water is cleaner because it comes from deeper layers, but it can also contain toxins. Residents of rural areas, along with well water, receive eighty milligrams of nitrates daily from every liter of water they drink.
In addition, the nitrate content in tobacco is high enough to cause chronic poisoning in long-term smokers. This is another argument in favor of fighting a bad habit.
Nitrates in products
During culinary processing of products, the amount of nitrates in them is significantly reduced, but at the same time, violation of storage rules can lead to the opposite effect. Nitrites, the most toxic substances for humans, are formed at temperatures from ten to thirty-five degrees, especially if the food storage area is poorly ventilated, and the vegetables are damaged or have begun to rot. Nitrites are also formed in defrosted vegetables; on the other hand, deep freezing prevents the formation of nitrites and nitrates.
Under optimal storage conditions, the amount of nitrate in products can be reduced by up to fifty percent.
Nitrate poisoning
Blueness of lips, face, nails;
- nausea and vomiting, there may be abdominal pain;
- yellowness of the whites of the eyes, bloody stools;
- headache and drowsiness;
- noticeable shortness of breath, palpitations and even loss of consciousness.
Sensitivity to this poison is more pronounced under conditions of hypoxia, for example, high in the mountains or with carbon monoxide poisoning or severe alcohol intoxication. Nitrates enter the intestines, where natural microflora metabolizes them to nitrites. Nitrites are absorbed into the systemic circulation and affect hemoglobin. The first signs of poisoning can be replaced within an hour with a large initial dose or after six hours if the amount of nitrates was small.
It should be remembered that acute nitrate poisoning is similar in its manifestations to alcohol intoxication.
It is impossible to separate our lives from nitrates, because this will affect all areas of human life: from nutrition to production. However, you can try to protect yourself from excessive consumption by following simple rules:
Wash vegetables and fruits before eating;
- store food in refrigerators or in specially equipped rooms;
- drink purified water.
Earlier nitrates blamed for all poisonings and gastrointestinal disorders. In the era of supermarkets and genetic engineering, the fear of fertilized vegetables and fruits faded into the background - we began to be frightened by waxed apples and giant strawberries. But nitrate farming did not remain in the last century. Are nitrates as scary as they are made out to be?
Nitrates- (nitric acid salts) are needed by plants for growth. Since nitrates are highly soluble in water, they move from the soil into groundwater and can therefore accumulate in plants that were originally grown without the use of fertilizers. Nitrates themselves are low toxic. But in the human body they can turn into nitrites. The latter are dangerous because they convert hemoglobin into methemoglobin, which loses its ability to deliver oxygen to tissues. True, the body has the enzyme methemoglobin reductase, which quickly returns hemoglobin to its normal state. Most nitrates are in the fruit growth zone, where protein synthesis occurs. For example, in the stalk and top leaves of cabbage, in the tails of cucumbers, in potato peels. Therefore, it is recommended not to use them for food. Each type of plant has its own characteristics of growth and development, for example, beets, radishes, lettuce, and cabbage accumulate nitrates more than others. But apples and strawberries nitrates almost indifferent. How much nitrates accumulate in fruits depends on the degree of their ripeness (green salts of nitric acid contain more) and growing conditions. If the plant has been fed with nitrogen fertilizers for a long time, then nitrates will accumulate in the fruits. Vegetables and fruits grown in greenhouses contain more nitrates than ground ones due to the high temperature in greenhouses. When plants grow, they constantly take the necessary nutrients from the ground, and nitrogen fertilizers are constantly added to the soil.
Daily maximum intake nitrates into the body - 5.0 mg per kg of body weight. In other words, a 70-kilogram person can quite easily eat 11 kilograms of strawberries or 200 grams of green salad. Poisoning with nitrates is a rare case; for example, to be poisoned by nitrates, you need to eat five kilograms of the same green salad.
Most often, intoxication is caused by microbes. For example, in the case of watermelon poisoning, many believe that nitrates are to blame, but in fact watermelon poisoning is of microbial origin. In markets, on patches and on roadsides, watermelons are piled up on the ground - all the bacteria that are in the air settle on them. Therefore, never buy a watermelon outside a store, and certainly do not ask the seller to cut a watermelon for you to check how red and sweet it is.
To reduce the amount nitrates in vegetables and fruits, peel them and put them in cold water for 20 minutes. Any heat treatment also benefits the fruit. But the main thing is not to faint at the mere mention of nitrates. According to WHO recommendations, an adult should eat at least 450 grams of vegetables and fruits per day. If you eat half a kilo of apples from the supermarket, your body will receive 8 mg nitrates, that is, the daily norm for a baby weighing two kilograms. So don't deny yourself watermelons and apples for dessert.
Which we absorb with vegetables and fruits are salts of nitric acid. Simply - saltpeter, as it was called before. Why should a farmer bother with cow or horse manure (this stuff, by the way, you won’t find during the day these days), if you can generously add inorganic fertilizers for lush growth? Have you ever seen black spots on the cut when peeling potatoes? Most likely, it was fertilized with nitrate fertilizers. Well, how do you go about all this? After all, health primarily depends on what we eat. And we often eat vegetables, stuffed with nitrates. I'm not a chemist, I'm simplifying, but the problem is relevant.
The presence of nitrates in plants is normal if it is within normal limits. But with an excess of nitrates, vegetables can be quite toxic.
How do nitrates enter the human body?
Most of the nitrates end up in organism with canned or fresh vegetables (approximately 50% of the daily value);
A very small amount - with milk and baked goods;
A small part is in fresh meat and fish, but their amount increases sharply when nitrates are added for the purpose of long-term storage;
Through drinking water. Nitrates from fields enter groundwater and then into water intake systems.
Why are nitrates dangerous?
Nitrates contribute to the formation of methemoglobin in the blood, which is unable to deliver oxygen to organs and tissues, resulting in possible suffocation. Liver function is disrupted and blood pressure drops. The limit is considered dangerous when the level of methemoglobin in the blood exceeds 20 percent. Nitrates are especially harmful to young children, since their enzymatic system has not yet formed.
How to deal with nitrates
The accumulation of nitrates depends not only on the application of mineral fertilizers. Their quantity also depends on the vegetable itself, where it grew - in a greenhouse or in open ground, in the shade or in the sun. The amount of nitrates varies in different parts of the plant.
Some practical tips
Pre-washing and peeling reduces the amount of nitrates in vegetables by 10 percent;
Their peel contains the most nitrates, so in some cases it would be a good idea to peel it;
Ripe fruits contain less nitrates than green ones;
- in the leaves of celery, parsley and dill there are 2 times less of them than in the stems;
In white cabbage leaves, 2/3 of the nitrates are in the stalk;
There are 70 percent fewer of them in the surface part of the carrot than in its core;
Radishes and cucumbers have 60 percent more nitrates in their skins than in their inner parts (it’s better to peel cucumbers);
- watermelon and melon do not need to eat the green pulp adjacent to the rind;
Eat only freshly prepared salads. Even their short-term storage in the refrigerator contributes to the transformation of nitrates into more dangerous nitrites;
Drinking green tea neutralizes nitrates entering the body.
By using these tips, you will definitely reduce your nitrate levels. But you don’t need to try to get rid of them completely. This is impossible, even harmful. Since vitamins, including vitamin C, are also destroyed at the same time.
Carefully! Early watermelons! VIDEO
Leave a comment